Faceted searching provides users with an incremental search and browse experience that lets them begin with a keyword search and go through the search results in an organized and simple way. Faceted searching, in many occasions, is used to serve up maps of the search results that may provide useful insights into the organization and content of these search results. Faceted navigation also allows users to systematically narrow down the search results in a fairly simple manner. Due to its many advantages, faceted search and navigation is being deployed rapidly across a wide variety of contexts and platforms. Unfortunately, the way facet engines work is too slow and very memory intensive, which prevent these types of search engines from performing better and scaling.
Therefore, there is still a need of accurate, fast and scalable faceted search engines.